NEWS and EVENTS

Prof. Dongming Fan research team published academic paper on top journal of Geosciences

Satellite gravity
surveying is currently a worldwide hot topic in the area of Geodesy. For the
first time, the gravity satellite GRACE (Gravity Recovery And Climate
Experiment) provides gravity measurements for nearly 15 years. Those
observations are unprecedented high-precision data for earth physical
phenomenon such as global hydrological signals, climate extreme anomalies,
seismology. GRACE opened new era of high-precision global gravity measurements
and climate- change experiments. It is also a powerful tool for the monitoring
of the global environmental change (melting of continental glacial, change of
sea level and ocean circulation, change of land water storage, intense
earthquake).

The satellite gravity
research team of our faculty led by Prof. Dongming Fan devoted to the
computation and application of high-precision static and time-varying earth
gravity model over a long-period of time. The researchers carried out by Prof.
Dongming Fan research team have attracted attentions at home and aboard. Recently,
the team member PhD candidate Yanchao Gu wrote a paper under the directions of
Prof. Dong Fan and Dr. Wei You. The paper was later published by the journal of
Geophysical Research Letters which is an international top journal in the area
of Geosciences. It’s the first time for SWJTU to be the first sign unit of the
papers from this journal. The paper received high comments from reviewers
(Reviewer's comments: This paper is the first to do systematic comparisons
across both the various GPS and GRACE solutions. This allows them to quantify
which of the IGS solutions are discrepant with respect to the others, and to
quantify one component of the error in the GPS time series)。 This highly approved that the
researches of the discipline of mapping and surveying are
keeping up with the international academic front-line, and are able to solve
the problems in the large-scale monitoring via high-precision satellite surveying techniques.

Tidal and non-tidal mass variations on the Earth’s
surface induce crustal vertical displacements (CVD) due to the elasticity of
the Earth’s crust. The tidal loading models are accurately modeled so that they
can be removed during data processing of GPS and other space geodesy systems.
However, the non-tidal models are still deemed to contain large uncertainties.
The sources of the differences between GPS and GRACE data are a challenging
problem, which needs to be fully resolved before considering the use of
combined GRACE and GPS data in Earth system science, in applications such as
correcting the non-tidal effect in GPS data processing.

The paper published on GRL shows that The result of the
cross comparison indicates that the non-tidal effects represented by the GRACE
solutions can explain as much as 50% of the GPS common signals, and more than
80% of the GPS annual signals. The results of the paper strongly suggest that
most of the residuals between GPS and GRACE CVD data can be attributed to GPS
post-processing errors, and the effects of the coarse resolution of the GRACE
products and other influencing factors are insignificant with respect to the
large inaccuracy of GPS estimates. The GRACE CVD data are robust and hence have
great potential to correct the non-tidal loading in GPS time series.